Anatomy of the Calcaneal Tendon of the Rabbit

Abstract

1. Certain macroscopical and microscopical features of the tendo calcaneus of the rabbit are described and illustrated, and the vascularisation as revealed by Spalteholz clearing is presented. 2. The vessels of the epitenon are chiefly derived from proximal and distal sources. 3. The vessels of the paratenon are derived from the main arteries of the leg. 4. The two vascular systems are largely independent of each other except along one edge of the tendon by way of a mesotenon. 5. The paratenon, epitenon and mesotenon and the related vessels are comparable to those found in tendons with synovial sheaths. By inference and from evidence obtained by dissection on the living human subject it is suggested that the arrangements are similar in the human tendo calcaneus. 6. Considerable friction develops on movement between the surfaces of the paratenon and epitenon. This might be significant in pathological states of the human tendon.

Structure and Function of Mammalian Tendon

“…The tendon lies within a sheath of loose connective tissue, the paratenon or, where a change of direction or increase friction necessitates more efficient lubrication, within a sheath with both parietal and visceral layers which are continuous through the mesotenon and which contain synovial-like fluid (Mayer, 1916(Mayer, ,1952Nisbit, 1960; Bunnell, 1956). T h e epitenon, a delicate layer of loose connective tissue covering the tendon, continues into its interior as the endotenon, intervening between the component bundles and carrying small blood vessels, lymphatics and nerves.…”

“…As tendon is a predominantly extracellular tissue with low metabolic requirements, its blood supply in the adult is scanty. These findings were augmented by histological and radiological studies of the blood supply to the tendo calcaneus (Lagergren & Lindholm, 1959; Nisbit, 1960) and by a study of the supply to the long tendons of the fingers where the vessels in the paratenon lie in curves which may be straightened during movement, whereas those in the mesotenon lie either in arcades or within the vinculae (Brockis, 1953). Other small vessels enter by the paratenon, branching several times in the long axis of the tendon and, where there is a synovial sheath, a plexus traverses the mesotenon; the osteo-tendon junction, however, is not an important site of entry (Edwards, 1946).…”

The functional characteristics of tendon blood circulation in the rabbit hindlimbs.

“…In particular, the existence of longitudinal vessels with numerous transverse branches appears to be essential for the explanation of our higher level of tendon blood flow and Pot at rest compared with the muscle. Judging from the investigations on paratenon and mesotenon (MAYER, 1916;EDWARDS, 1946;NISBET, 1960;SMITH, 1965) and the functional and the anatomical basis of non-nutritive circulation in the tendon (BARLOW et al, 1961;GRANT and WRIGHT, 1970), the regional differences and time-dependent changes in tendon blood flow in the present experiments seem to be fully or partially dependent on the activity of non-nutritive channels and/or segmental blood vessels, and its regulation by other factors (see below). Since it is known that the tendon is a predominantly extracellular tissue with low metabolic requirements (ELLIOTT, 1965), the blood flow is considered to play another important role.…”

The impact of polyglycolide membrane on a tendon after surgical rejoining. A histological and histomorphometric analysis in rabbits

“…It arises from the soleus muscle and inserts into the posterior calcaneus. The plantaris longus tendon is the most posterior tendon, overlying the two aforementioned tendons 19…”